Most OEM bars are actually made of PU (polyurethane) and although there are advantages like shock absorption there are a few downsides. For instance polyurethane can be harder to repair, moulds are more complex and cost more which increases part cost, harder to modify for fitting. The hardest part of selling bodykits for R33's is that series 1 and 2 are slightly different in the front end which makes trying to design a bar that fits both challenging to say the least. This might sound like a sales pitch as I sell fibreglass bodykits, however I have numerous PU suppliers but both styles available and cost has led us to selling fibreglass. I believe that bodykits are very cheap these days. Some people are still charging excess of $1000 for very average fitting kits which fit just as good as the dirt cheap ones. Having said that though, buyers need to be aware that every car is different and might have previous damage that can affect fitment.